BAG CELLS AT REST AND SEVERAL DAYS AFTER ISOLATION AND REGENERATION, SHOW A RELATIVELY PREDICTABLE AND STABLE CALCIUM EFFLUX ACROSS THE SOMA PLASMA MEMBRANE (SMITH ET AL. BIOL. BULL. 185: 293-294, 1993; SMITH ET AL. METHODS IN CELL BIOLOGY 40: 115-134, 1994). AN INDUCED FREE-RADICAL ATTACK, BROUGHT ABOUT BY THE ADDITION OF HYDROGEN PEROXIDE TO THE MEDIUM (2.5, 5 & 10~MOL.L-1 ) RAPIDLY CAUSES THIS PATTERN TO REVERSE IN A TRANSIENT MANNER, WITH THE EVENTUAL LOSS OF EFFLUX AND CELL DEATH (SMITH ET AL. BIOL. BULL. 185: 293-294, 1993; DUTHIE ET AL. FREE RAD. RES. 20: 307-313, 1994). CONCOMITANT ANATOMICAL CHANGES ARE PROFOUND. WITHIN MINUTES OF THE ATTACK, BUT AFTER PHYSIOLOGICAL PERTURBATION, THE GROWTH CONES BEGIN TO RETRACT, THE SOMA SWELLS AND NEURITES ARE REABSORBED OR BREAK UP. IN MANY CASES THE CELLS LYSE. THE ADDITION TO THE MEDIA OF KNOWN CHELATORS OF TRANSITION METALS AND SCAVENGERS OF FREE-RADICALS PREVENTS THESE EFFECTS FOR AT LEAST 24H (MANNITOL, SODIUM BENZOATE, ALBUMIN AND 2,2~ DIPYRIDYL). FROM THIS DATA WE PROPOSE THAT DAMAGE INITIATED AND PROPAGATED BY REACTIVE FREE RADICALS IS MODERATED BY ANTIOXIDANTS.